The present invention relates to an aggregate for feeding fuel from a supply tank to an internal combustion engine of a motor vehicle.
More particularly, it relates to a feeding aggregate with a flow pump having an impeller with a plurality of vanes rotatable in a pump chamber.
Feeding aggregates of the above mentioned general type are known. One of such aggregates is disclosed in the German reference DE 40 20 521 A1. This aggregate has a flow pump with an impeller having a plurality of vanes on its periphery at both end surfaces. The impeller is arranged in the pump chamber which is limited by a wall part in direction of the rotary axis of the impeller and also limited by a housing part in a radial direction. In the end faces of the wall part facing the impeller correspondingly ring-shaped feeding passages are formed. One of such feeding passages communicates through a suction opening with a suction side of the flow pump and the other feeding passage communicates through a pressure opening with the pressure side of the flow pump. An intermediate space is formed between the vanes of each end side, and the intermediate spaces of the vanes formed at both end sides are connected with one another through axial passages in the impeller.
In the region of the suction opening the fuel flows on the one hand directly in the feeding passage in which the suction opening opens, and on the other hand flows from it through the intermediate spaces and through the passages in the impeller to the feeding passage arranged at the opposite end surface of the impeller. Correspondingly, fuel flows directly from the feeding passage from which the pressure opening extends and also flows from the feeding passage arranged at the opposite end surface of the impeller, through the passages in the impeller and is discharged from it through the pressure opening. The passages through which the fuel flows between both end surfaces of the impeller represent throttling points which hinder the flow of the fluid and thereby worsen the efficiency of the flow pump. Since the whole inflow of the fuel is performed through one side of the impeller, in the suction region of the fuel pump there is a strong pressure drop, which especially in the case of high fuel temperatures contributes to the production of vapor bubbles which disturb the operation of the feeding aggregate.